Phonographic recording apparatus.



No. 688,6!0. Patented Dec. l0, I901.

T. A. EDISON. V PHONOGBAPHIC RECORDING APPARATUS.

(Application filed Mar. 17, 1899.) (No Model.)

m: NORRIS Pans cc. more-Lima, WASHINGTON, a c.

NITED STATES Par).

PHONOGRAPHIC RECORDING APPARATUS.

SPECIFICATION forming part of Letters Patent No. 688,610, dated December10, 1901.

Application filed March 17, 1899.

T ztZZ whom it may concern;

Be it known that I, THOMAS A. EDISON, a citizen of the United States,residing at Llewellyn Park, in the countyof Essex and State of NewJersey, have invented a certain new and useful Improvement inPhonographic Recording Apparatus, (No.1,003,) of which the following isa specification.

My invention relates to various improvements in apparatus for makingphonographic records; and the object of the invention is to improve thesensitiveness and accuracy of the recording mechanism.

The invention consists in so arranging the diaphragm or otherelementinfluenced or vibrated by the sound-waves as to normally relieveit of all or substantially all stress,whereby it will be maintained insubstantial equilibrium and will be more sensitively recep tive and moreaccurately responsive to soundvibrations. t

In phonographic recorders as heretofore constructed the diaphragms orequivalent devices have either been placed under a strain by thecompensating weight employed to cause the cutting or engraving tool toproperly track upon the recording-surface and at the same time toaccommodate any eccentricities or variations in the blank or in caseswhere no weight is employed for this purpose the pressure necessary toproperly engage the cutting or engraving tool with the recordingmaterial to the requisite depth to record the movements of the diaphragmunder the sound-vibrations of itself places the diaphragm under stress.These strains destroy to a great extent the sensitiveness of thediaphragm or other vibrating element, especially to the weak overtonesof musical instruments, and prevent the accurate recording thereof.

In order to overcome the objection indicated, the invention consists inemploying a counteracting-spring cooperating with the diaphragm andwhich counteracts the normal strains to which the diaphragm may besubjected, either due to the employment of the usual compensating weightor to the direct engagement of the recording device with the record, aswith some types of phonographrecorders.

In the accompanying drawings, Figure 1 is Serial No. 709,448. (Nomodel.)

a sectional view through a phonograph-recorder of the typeemployingacompensating weiglit, illustrating my present improvementsapplied thereto, including the employment of a secondary or auxiliaryspring; Fig. 2, a bottom view of the same; Fig. 3, a section onthe lineX X of Fig. 2.

In all of the above views corresponding parts are represented by thesame numerals of reference.

1 is the usual cylindrical casing, having a top 2, provided with anipple 3, to which the speaking-tube is secured.

4 is the diaphragm, held in place between the rubber buffers 5 5, and 6the clampingring for forcing the top 2 upon the upper buffer.

7 represents the compensating weight, piv-c oted at 8, and 9 therecording-lever, carrying the cutting or engraving tool 10 at one end,which engages with the recording-surface 11, generally in the form of acylinder. The lever 9 is pivoted at 12 to the compensating weight 7 andconnects at its 'free end by a link 13 with a small disk 14, secured tothe center of the diaphragm 4 in any suitable way, as by means ofshellac. Preferably I employ an auxiliary spring 15, connected to oneend of the weight 7, as shown, and at the other end by a link 16 to theworking end of the lever 9. This spring tends to depress the cutting orengraving tool 10 with an additional tension into engagement with therecording-surface and prevents successive vibrations of the cutting orengraving tool from the effects of momentum or the actual jumpingthereof when subjected to the effect of unusually powerful vibrations.An adjusting-screw 17 is employed for adjusting the tension of thespring when used.

Heretofore the tendency of the compensating weight 7 has been to exert adownward stress upon the diaphragm 4, and by reason of this stress thediaphragm is not affected sensitively by the vibrations, nor does itrespond accurately thereto. I therefore provide for the elimination ofany stress upon the diaphragm,whcreby it will be maintained insubstantial equilibrium, for the reasons which I have explained. Withadevice of this character either a counteracting spring or weight may beemployed, the former being preferable with the specific form of recordershown.

This counteractin zs rim 18 is secured to the bottom of the casing 1,passes abovea bridge 19, and at its free end bears beneath the disk 14,a section of rubber 20 or other elastic material being interposedbetween the spring and said disk to prevent any rubbing sounds frombeing recorded. An adjusting-screw 21 engages through the bridge 19 andbears againstthe counteracting-spring 18, whereby.

the exact stress or strain which is exerted upon the diaphragm 4 by thecompensating weight 7 and the auxiliary spring 15, if used, may beremoved from the diaphragm and taken up.

by the spring 18. In this way the diaphragm will be maintained inabsolute equilibrium, normally as much so, in fact, as if there were @noconnectionwhatever between it and the Therefore it. is in a' recordingmechanism. condition to respond sensitively to vibrations of everycharacter and to accurately record them. At the same time the connectingmechanism between the diaphragm and the cutting or engraving tool willbe under stress, whereby thecutting or engraving tool will respond toall vibrations, however abrupt,without lost motion or false motions dueto mo- .mentutn.

Having now described my invention, what I claim as new, and desire tosecure by Letters Patent, is as follows:

1. In a phonographic recording device, the

combination with a diaphragm, of a record- .ing device connectedtherewitha counteracting-.spring'for counteracting the stress imposednpon the diaphragm by the engagevment of the recording device with therecording-surface, andan elastic cushion-between thecounteracting-spring and the diaphragm,

.snbstantialiyas set forth.

2. In a phonographic recording device, the combination With a diaphragm,of a compensating Weight, a recorder connected with the diaphragm andsaid compensating weight, and means for counteracting the stress imposedupon the diaphragm by the compensating weight, substantially as setforth.

3. Ma phonographic recording device, the combination with a diaphragm,of a compensating weight, a recorder connected with the diaphragm andsaid compensating weight, and a spring connected with the diaphragm forcounteracting the stress imposed upon the diaphragm by the compensatingweight, substantially as setforth.

4. In a phonographic recording device, the

combination with a diaphragm, of a compenbetween the diaphragm and saidweight, of

an auxiliary spring carried by said weight and connected With therecording devices, and meansfor adjusting the tension of said auxiliaryspring, substantially as set'forth.

7. Ina phonographic recording device, the combination with adiaphragm,ofa compensating weight, a recordingdever pivoted to said weight andcarrying at one end a cutting or engraving tool, a'link connecting theother end of said lever with the diaphragm, and an adjustable springcarried by the compensating weight and connected at its free end to theworking end of the recording-lever, substantially as set forth.

This specification signed and witnessed this 10th day of February, 1899.

THOMAS A. EDISON.

Witnesses:

ALEXANDER ELLIOTT, Jr. JOHN F. RANDOLPH.

